They were not confirmed to be true love’s on the show ever, but you are not going to change my mind and i am not going to change your mind, so let’s just let that be.
It isn’t a matter of opinion. It was said on the show multiple times, and stated. Whether you choose to accept it or not is up to you.
Firebird, Season 5 Episode 20. Confirmed true love when they went to open the doors in the Underworld to get ambrosia.